The present invention relates generally to flattened drinking straws, methods of making them, and a dispenser therefor which includes means for reconstituting the flattened tube into a tubular straw prior to use.
It is known in the art to collapse drinking straws for ease of storage and handling. U.S. Pat. No. 5,067,629 to Schwartz, for example, discloses drinking straws which are packaged by providing a plurality of flexible, hollow, cylindrical tubes arranging the tubes in parallel and pressing the tubes to force them into a substantially flattened configuration. Note FIG. 4 which discloses a drinking straw supply cartridge in accordance with the ""629 patent.
U.S. Pat. No. 3,780,944 to Zubalik discloses drinking straws which are compacted for storage and attached to individual beverage containers. The drinking straws are compacted for storage by folding and flattening and attached to a beverage can for example. See FIG. 1 as well as FIG. 10.
U.S. Pat. No. 1,680,341 to Rosenthal relates to a bottle closure which is adapted to contain the straw that is flattened and coiled or otherwise laid upon itself such that the straw occupies little space. See FIGS. 3 and 6 and page 1, lines 103-105.
Collapsible drinking straw systems have not met with substantial commercial success, perhaps due to the fact that prior systems did not utilize suitable materials, or that the prior art systems were simply not convenient enough for widespread acceptance. A further drawback is that conventionally applied materials tend to permanently crease and crack. There is provided in accordance with the present invention a robust system for producing collapsible drinking straws which readily regain their original shape as will be appreciated from the discussion hereinafter.
There is provided in accordance with the present invention a drinking straw for consuming a beverage prepared by way of a process including: a) melt-extruding a polymeric material in the shape of a continuous tubular conduit, suitable for preparing a plurality of drinking straws, the conduit being provided with a central longitudinal cavity; b) cooling the continuous tubular conduit to a temperature of below the softening point of the polymer; c) flattening the tubular conduit so as to collapse its structure into a substantially planar form, thereby constricting the central longitudinal cavity and reducing the volume of the continuous tubular conduit; d) cutting a length from the continuous conduit of suitable dimensions for making the straw; and e) dilating the length of the conduit so as to restore the cross sectional area of the central longitudinal cavity thereby reconstituting its tubular structure.
In particular embodiments one may perform the cutting operation prior to dilating the straw back to its original structure; whereas in other embodiments one may prefer to dilate the structure of the straw prior to cutting the length from the continuous conduit. As used herein, the term xe2x80x9ccontinuousxe2x80x9d refers to the fact that the conduit is suitable for making a plurality of straws. Typically this would include more than ten straws and up to perhaps several hundred straws or even more. Traditionally, drinking straws have been tubular in nature, that is, having cylindrical tubes with thin walls and relatively large inner openings for conveying fluids. Because of this relatively large inner opening, the packaging, shipping and handling of straws is inherently inefficient in that a majority of the space within a package of straws is empty. The current invention addresses this space issue and also relates to improve efficiencies in the manufacture and dispensing of straws.
Although flattened drinking straws are known, prior art straws were manufactured in a conventional fashion and then flattened subsequent to cutting. The present invention describes a process to produce flattened straws in a continuous fashion whereby the flattened straw is reeled up in coil and then is packaged and shipped to a place of use in a highly compact manner. The coiled straw is then reconstituted and cut to a length in a dispenser that incorporates a means to uncoil, reshape and cut the straw.
In the manufacture of plastic straws, a molten thermoplastic is extruded through a dye to form a continuous tube. This tube is cooled below the softening temperature of the polymer and is then cut to the appropriate length. Typically this is done in a high speed process. The speed of this process is generally limited by the speed of the cutting step. After cutting the straws are either wrapped and packaged or simply packaged for shipment. In the process in the current invention, the straw is formed, extruded, cooled and then put through a slot or pinch roller that partially flattens the straw. The straw, rather than being cut, is rolled up on a reel. Although conventional straws could be put through this flattening process, a solid polymer straw could develop a permanent crease or crack at the fold. The preferred material for the straw in the process of the invention is a straw made from a microcellular foam.
The preferred microcellular foams offer the advantage of reduced weight, increased crack and tear resistance and high resiliency. The microcellular foams are characterized by having a foam cellular structure that has relatively uniform void spaces. Although the actual size of the cells can range from 100 microns down to sub-micron level, with any given foam structure, these cell spaces have a narrow size distribution range. The properties of the foam polymers are influenced not only by the size of the cells, but also the number of cells per unit volume. In general the higher number of cells in a given volume, the lower the density. For straws, the desired cell size is usually in the range of from about 5 to about 70 microns and the desired density is in the range of from about 50 to about 75 percent of the solid polymeric material forming the straw.
The polymers used in the straw making process is suitably any flexible thermoplastic polymer compatible with extrusion to annular die. These polymers include polyethylene, polypropylene, crosslinked or partially crosslinked polyethylene or polypropylene, polyolefins generally, polystyrene, nylon, polyether amides, thermoplastic elastomers, such as styrene-butadiene elastomer copolymers (eg. Kraton(copyright)) or styrene-acrylonitrile copolymer elastomers (referred to as polystyrene elastomers herein) polycarbonates, and polycarbonates/acrylonitrile blends or butadiene blends. Other thermoplastic polymers may be used; however, the least costly polymer will typically be the polymer of choice. Since straws are inherently a disposable item, polypropylene is the material of choice both from a cost standpoint and a performance standpoint.
The current invention is compatible with straws of all common dimensions. Typical straws have a side wall thickness of from about {fraction (1/64)} to {fraction (1/16)} inch with inside diameters that range from {fraction (1/16)} inch up to about xe2x85x9c of an inch. Lengths of straws range from 3 inches up to about 12 inches, but the most common length is 7xc2xd inches to 7xc2xe inches.
As an example of the space economy associated with the flattened straw of the current invention, a four inch coil (with a one inch core) of straws with {fraction (1/64)} inch side wall, a xc2xc inch outside diameter, and a 7xc2xe inch length would provide approximately 48 straws and would take up a volume of approximately 4.7 cubic inches. A stack of 48 conventional straws would occupy a volume of 37.75 cubic inches. The coil of straws (even with a one inch core) occupies only 12.5 percent of the volume of the conventional straws. Thus significant economies can be realized by flattening and coiling the straws. The flattened straws would then be reshaped and cut into lengths in the straw dispenser as described here and after.
In particularly preferred embodiments the extruded polymeric material comprises a mixture of a supercritical fluid foaming agent and a polymer. Preferred supercritical fluid foaming agents include high pressure CO2 and high pressure N2. As noted above, the straws are formed from microcellular polymer foams of relatively uniform cell size which may have a foam cell size of from about one micron and up to about 100 microns. Preferred cell sizes for straws are in the range of from about 5 microns to about 70 microns.
The wall density of the straw is typically from about 50 to about 75 percent of the density of the polymer forming the foam matrix in such embodiments. Particularly preferred polymer materials include polyethylene, polypropylene, (polyolefins), polystyrene, nylon, polyetheramides, thermoplastic elastomers, such as Kraton(copyright) and polycarbonates, and blends such as blends of polycarbonate/acrylonitrile and butadiene/styrene blends.
In another aspect of the present invention there is provided a method of making a drinking straw for consuming a beverage, wherein the process comprises: a) melt extruding a polymeric foam in the shape of a continuous tubular conduit suitable for preparing a plurality of drinking straws, wherein the conduit is provided with a central longitudinal cavity; b) cooling the tubular conduit to a temperature below the melting point of the polymer; c) flattening the continuous tubular conduit so as to collapse its structure into a substantially planar form, thereby constricting the central longitudinal cavity and reducing the volume of said continuous tubular conduit; d) dilating the length of the conduit so as to restore the cross-sectional area of the central longitudinal cavity thereby reconstituting its tubular shape; and e) cutting a length from the continuous tubular conduit of suitable dimension for making the straw.
In still yet another aspect of the invention there is provided a drinking straw dispenser including a) a continuous polymeric tubular conduit of suitable length for preparing a plurality of drinking straws, the continuous tubular conduit having a central longitudinal cavity; b) reel means for receiving the continuous polymeric tubular conduit wherein the continuous conduit is wound thereabout in substantially planar form such that the central longitudinal cavity of the polymeric tubular conduit is constricted and the volume of the continuous polymeric tubular conduit is thereby minimized; c) means for dilating the continuous tubular conduit as it is unwound from the reel include, for example, a pair of pinch rolls. There is also provided in the drinking straw dispenser (d) means for cutting the straw which could be a heated wire or a razor blade, a clipper or a scissors type cutter or even a relatively high powered laser. In particular embodiments a guillotine type cutter may be employed.